The present invention relates generally to a conveyor apparatus, such as an escalator or a passenger conveyor. More specifically, the invention relates to a conveyor apparatus having a long moving distance.
An escalator as an example of a conveyor apparatus has a plurality of treads which have guide rollers in the front and rear portions thereof. The plurality of treads are designed to be supported by the engagement of each guide roller with a tread guide rail which is installed in a structure, to move in a horizontal direction in the vicinity of the landing stage and head of the escalator while being maintained horizontally, and to move in an ascent or descent direction of about 30 degrees on the way from the vicinity of the landing stage to the vicinity of the head of the escalator. Usually, the plurality of treads are connected to each other by means of a chain. By driving this chain, all of the treads are designed to closely move in synchronism with each other.
As a drive unit for driving the chain, a system of a type for driving the end portion of the chain by means of a sprocket is adopted. This system is provided in the vicinity of the landing stage or the head of the escalator. However, in an escalator having a large floor height, the load applied to the chain is large, so that there are some cases where sufficient driving force can not be transmitted only by driving the end portion of the chain. Such a problem is not only limited to escalators, but it is also con to all of conveyor apparatuss having a long moving distance
Conventionally, in order to move a series of long treads in an escalator having a large floor height or a passenger conveyor having a long moving distance, it has been proposed that drive units capable of applying driving force on the way of a long chain (in a portion other than end portions in which the chain turns back) (such drive units are disclosed in, erg., Japanese Patent Publication Nos. 1986-19551, 1986-41834, 1986-41836 and 1987-9520) are distributed.
Each of these drive units for applying driving force on the way of the chain comprises: a motor serving as a driving source; a reduction gear for amplifying driving force by over ten; and a chain driving force transmitting mechanism for transmitting the driving force to a stretching chain. If a sprocket is adopted as the chain driving force transmitting mechanism the contact ratio decreases since the chain is not wound onto the sprocket, therefore, as shown in, e.g., FIGS. 17(a) and 17(b) , in the chain driving force transmitting mechanism, a chain connected to treads 102 is formed as a toothed chain 105, and a driving side is formed by a driving sprocket 106 having a pin roller 108, so that the chain driving force transmitting mechanism utilizes the engagement of the pin roller 108 with the toothed chain 105.
However, the conventional chain driving force transmitting mechanism 100 shown in FIG. 17 requires special components, such as the toothed chain unlike a simple driving mechanism utilizing a chain sprocket for use in usual escalators.
In addition, since the toothed chain uses a long pitch link, the velocity of the end of one pitch of the toothed chain is more ununiform in the turning portion of the toothed chain than the usual chain, so that the toothed chain is turned back by means of a pseudo circular guide rail although the usual chain is turned back by means of a sprocket. Therefore, it is difficult to use an inexpensive standard driving mechanism, which is driven by a circular sprocket rotating at a constant velocity, in the turning portion.
The inventor found a reduction gear using a trochoid tooth profile for carrying out a linear driving before the present invention has been made. Such a reduction gear is disclosed in, e.g., Japanese Patent Laid-Open Nos. 5-187502, 6-174043 and 9-105446, and is used in the field of industrial robot, automatic machine and so forth.
For example, as shown in FIG. 18, Japanese Patent Laid-Open No. 9-105446 discloses a reduction gear wherein pins 106 are mounted on a translation body 107 at regular intervals (even pitches) along the translation body 107, and if an eccentric crank 108 connected to a motor makes one rotation, an oscillating plate 111 having a trochoid tooth profile 110 makes one oscillation, so that the portion of the trochoid tooth profile 110 moves the pins 106 forward by one pitch at a constant velocity. That is, according to this reduction gear, the translation body 107 moves by one pin pitch per one rotation of the motor. Conventionally, such a mechanism has been utilized as a reduction gear for an industrial robot or the like.
It is therefore an object of the present invention to provide a conveyor apparatus which can be applied to an escalator having a large floor height, a passenger conveyor having a long moving distance and so forth and which is capable of being a single driving mechanism serving as two mechanism elements of both a reduction gear and a chain driving force transmitting mechanism which have been conventionally essential for conventional driving mechanisms.
It is another object of the present invention to provide a conveyor apparatus which has a distributed driving mechanism using a conventional inexpensive standard conveyor drive unit of a chain sprocket in a chain turning portion and which is capable of being used with conventional drive unit.
In order to accomplish these other objects, a conveyor apparatus according to the present invention comprises: a tread guide rail which is provided on a structure; a plurality of treads which move along the tread guide rail; a chain having a pin roller and connecting the plurality of treads in the form of an endless loop; a rotation drive unit which is mounted on the structure; and driving means for converting a rotational motion, which is transmitted fruit the rotation drive unit via an eccentric shaft, into an oscillating motion of an oscillating body having a trochoid tooth profile, to give thrust to the pin roller which engages the trochoid tooth profile.
The driving means preferably comprises an eccentric crank shaft which is connected to the rotation drive unit and which eccentrically rotates; an oscillating body which is connected to the eccentric crank shaft and which oscillates in accordance with the eccentric rotation of the eccentric crank shaft; and trochoid-shaped pin roller rolling teeth which are provided on an end portion of the oscillating body and which give thrust to the pin roller in accordance with the oscillation of the oscillating body.
According to the conveyor apparatus of the present invention, the pin rollers of the chain are arranged at regular intervals (even pitches) by the links of the chain, and are guided on the tread guide rail, so that the pin rollers are arranged in the same state as pins mounted on a translation body at regular intervals (even pitches). When the eccentric crank shaft rotates, the oscillating body oscillates, so that the pin roller contacting the trochoid tooth profile of the oscillating body can move forward by one pitch every one rotation of the eccentric crank shaft. In such a mechanism for converting rotational motion to oscillating motion of the trochoid tooth profile, the chain driving mechanism itself also functions an a reduction gear.